| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef MEDIA_BASE_VIDEO_DECODER_H_ |
| #define MEDIA_BASE_VIDEO_DECODER_H_ |
| |
| #include <string> |
| |
| #include "base/callback.h" |
| #include "base/macros.h" |
| #include "base/memory/ref_counted.h" |
| #include "media/base/decode_status.h" |
| #include "media/base/media_export.h" |
| #include "media/base/pipeline_status.h" |
| #include "media/base/waiting.h" |
| #include "ui/gfx/geometry/size.h" |
| |
| namespace media { |
| |
| class CdmContext; |
| class DecoderBuffer; |
| class VideoDecoderConfig; |
| class VideoFrame; |
| |
| class MEDIA_EXPORT VideoDecoder { |
| public: |
| // Callback for VideoDecoder initialization. |
| using InitCB = base::Callback<void(bool success)>; |
| |
| // Callback for VideoDecoder to return a decoded frame whenever it becomes |
| // available. Only non-EOS frames should be returned via this callback. |
| using OutputCB = base::RepeatingCallback<void(scoped_refptr<VideoFrame>)>; |
| |
| // Callback type for Decode(). Called after the decoder has completed decoding |
| // corresponding DecoderBuffer, indicating that it's ready to accept another |
| // buffer to decode. |
| using DecodeCB = base::Callback<void(DecodeStatus)>; |
| |
| VideoDecoder(); |
| |
| // Returns the name of the decoder for logging and decoder selection purposes. |
| // This name should be available immediately after construction (e.g. before |
| // Initialize() is called). It should also be stable in the sense that the |
| // name does not change across multiple constructions. |
| virtual std::string GetDisplayName() const = 0; |
| |
| // Returns true if the implementation is expected to be implemented by the |
| // platform. The value should be available immediately after construction and |
| // should not change within the lifetime of a decoder instance. The value is |
| // used for logging and metrics recording. |
| // |
| // TODO(sandersd): Use this to decide when to switch to software decode for |
| // low-resolution videos. https://crbug.com/684792 |
| virtual bool IsPlatformDecoder() const; |
| |
| // Initializes a VideoDecoder with the given |config|, executing the |
| // |init_cb| upon completion. |output_cb| is called for each output frame |
| // decoded by Decode(). |
| // |
| // If |low_delay| is true then the decoder is not allowed to queue frames, |
| // except for out-of-order frames, i.e. if the next frame can be returned it |
| // must be returned without waiting for Decode() to be called again. |
| // Initialization should fail if |low_delay| is true and the decoder cannot |
| // satisfy the requirements above. |
| // |
| // |cdm_context| can be used to handle encrypted buffers. May be null if the |
| // stream is not encrypted. |
| // |
| // |waiting_cb| is called whenever the decoder is stalled waiting for |
| // something, e.g. decryption key. May be called at any time after |
| // Initialize(). |
| // |
| // Note: |
| // 1) The VideoDecoder will be reinitialized if it was initialized before. |
| // Upon reinitialization, all internal buffered frames will be dropped. |
| // 2) This method should not be called during pending decode or reset. |
| // 3) No VideoDecoder calls should be made before |init_cb| is executed. |
| // 4) VideoDecoders should take care to run |output_cb| as soon as the frame |
| // is ready (i.e. w/o thread trampolining) since it can strongly affect frame |
| // delivery times with high-frame-rate material. See Decode() for additional |
| // notes. |
| // 5) |init_cb| may be called before this returns. |
| virtual void Initialize(const VideoDecoderConfig& config, |
| bool low_delay, |
| CdmContext* cdm_context, |
| const InitCB& init_cb, |
| const OutputCB& output_cb, |
| const WaitingCB& waiting_cb) = 0; |
| |
| // Requests a |buffer| to be decoded. The status of the decoder and decoded |
| // frame are returned via the provided callback. Some decoders may allow |
| // decoding multiple buffers in parallel. Callers should call |
| // GetMaxDecodeRequests() to get number of buffers that may be decoded in |
| // parallel. |
| // |
| // Implementations guarantee that the |decode_cb| will not be called from |
| // within this method, and that it will be called even if Decode() is never |
| // called again. |
| // |
| // After decoding is finished the decoder calls |output_cb| specified in |
| // Initialize() for each decoded frame. |output_cb| may be called before or |
| // after |decode_cb|, including before Decode() returns. |
| // |
| // If |buffer| is an EOS buffer then the decoder must be flushed, i.e. |
| // |output_cb| must be called for each frame pending in the queue and |
| // |decode_cb| must be called after that. Callers will not call Decode() |
| // again until after the flush completes. |
| virtual void Decode(scoped_refptr<DecoderBuffer> buffer, |
| const DecodeCB& decode_cb) = 0; |
| |
| // Resets decoder state. All pending Decode() requests will be finished or |
| // aborted before |closure| is called. |
| // Note: No VideoDecoder calls should be made before |closure| is executed. |
| virtual void Reset(const base::Closure& closure) = 0; |
| |
| // Returns true if the decoder needs bitstream conversion before decoding. |
| virtual bool NeedsBitstreamConversion() const; |
| |
| // Returns true if the decoder currently has the ability to decode and return |
| // a VideoFrame. Most implementations can allocate a new VideoFrame and hence |
| // this will always return true. Override and return false for decoders that |
| // use a fixed set of VideoFrames for decoding. |
| virtual bool CanReadWithoutStalling() const; |
| |
| // Returns maximum number of parallel decode requests. |
| virtual int GetMaxDecodeRequests() const; |
| |
| // Returns the recommended number of threads for software video decoding. If |
| // the --video-threads command line option is specified and is valid, that |
| // value is returned. Otherwise |desired_threads| is clamped to the number of |
| // logical processors and then further clamped to |
| // [|limits::kMinVideoDecodeThreads|, |limits::kMaxVideoDecodeThreads|]. |
| static int GetRecommendedThreadCount(int desired_threads); |
| |
| protected: |
| // Deletion is only allowed via Destroy(). |
| virtual ~VideoDecoder(); |
| |
| private: |
| friend struct std::default_delete<VideoDecoder>; |
| |
| // Fires any pending callbacks, stops and destroys the decoder. After this |
| // call, external resources (e.g. raw pointers) |this| holds might be |
| // invalidated immediately. So if the decoder is destroyed asynchronously |
| // (e.g. DeleteSoon), external resources must be released in this call. |
| virtual void Destroy(); |
| |
| DISALLOW_COPY_AND_ASSIGN(VideoDecoder); |
| }; |
| |
| } // namespace media |
| |
| namespace std { |
| |
| // Specialize std::default_delete to call Destroy(). |
| template <> |
| struct MEDIA_EXPORT default_delete<media::VideoDecoder> { |
| constexpr default_delete() = default; |
| |
| template <typename U, |
| typename = typename std::enable_if< |
| std::is_convertible<U*, media::VideoDecoder*>::value>::type> |
| default_delete(const default_delete<U>& d) {} |
| |
| void operator()(media::VideoDecoder* ptr) const; |
| }; |
| |
| } // namespace std |
| |
| #endif // MEDIA_BASE_VIDEO_DECODER_H_ |